Green Tea Catechins May Help Reduce Prostate Cancer and Lower PSA in Men at High Risk
Prostate cancer is the second most common type of cancer in
men and is predicted to result in an estimated 220,00 cases in the United
States in 2015. In recent years, an emphasis has been placed on chemoprevention
– the use of agents to prevent the development or progression of prostate
cancer. A team of researchers led by Nagi B. Kumar, Ph.D., R.D., F.A.D.A. at Moffitt
Cancer Center recently published results of a randomized trial that assessed
the safety and effectiveness of the active components in green tea to prevent
prostate cancer development in men who have premalignant lesions. The results
will be presented at the 2015 American Society of Clinical Oncology (ASCO)
Annual Meeting in Chicago.
Twenty percent of green tea is consumed in Asian countries
where prostate cancer death rates are among the lowest in the world and the
risk of prostate cancer appears to be increased among Asian men who abandon
their original dietary habits upon migrating to the U.S.
Laboratory studies have shown that substances in green tea
called, “catechins” inhibit cancer cell growth, motility and invasion, and
stimulate cancer cell death. Green tea
catechins also prevent and reduce tumor growth in animal models.
Epigallocatechin-3-gallate (EGCG) is the most abundant and potent catechin
found in green tea responsible for these cancer prevention effects.
The goal of this trial was to evaluate if a one-year
intervention with green tea catechins could suppress prostate cancer
development in men who had high-grade intraepithelial neoplasia (HGPIN) or
atypical small acinar proliferation (ASAP).
The researchers used decaffeinated green tea capsules called Polyphenon
E that contained a mixture of catechins that predominantly contained EGCG at a dose
of 200 mgs twice a day.
The researchers compared Polyphenon E in 49 men to placebo
tablets in 48 men over a 1 year treatment period. Overall, the difference in the number of
prostate cancer cases at the end of 1 year between the two treatment groups was
not statistically significant. However, in men who only had HGPIN at the
beginning of the trial, they observed a lower combined rate of ASAP and
prostate cancer development with Polyophenon E.
ASAP is an entity that reflects a broad group of lesions in the prostate
with insufficient changes in the cells to be definitively diagnosed as prostate
cancer. Additionally, men on Polyphenon
E had a significant decrease in prostate-specific antigen (PSA) levels. PSA is
a biomarker that in combination with other risk factors is used to screen
patients for prostate cancer, and high levels signify a higher risk of prostate
cancer.
The Moffitt researchers observed a significant increase in
the levels of EGCG in the blood plasma of men on Polyphenon E, and the capsules
at this dose were tolerated in this group of men.
The ASCO poster
session will take place Monday, June 1, 1:15-4:45 p.m. in S Hall A. The study
was published in the April 14 issue of the journal Cancer Prevention
Research. Funding support was received
from the National Institutes of Health/National Cancer Institute (R01 CA12060-01A1).
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